Assertion (A): A magnetic field changing with time gives rise to an electric field.
Reason (R): An electric field changing with time gives rise to a magnetic field.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
(A) A magnetic field changing with time gives rise to an electric field. — True. By Faraday’s law, a changing magnetic flux induces an emf. An emf between two points means that an electric field does work on the charge between them.
(R) An electric field changing with time gives rise to a magnetic field. — True. A changing electric field gives a displacement current \( \varepsilon_0\,d\Phi_E/dt \), which is a source of magnetic field just like a conduction current.
Why R does not explain A?
(A) is Faraday’s law of electromagnetic induction. (R) is its symmetrical counterpart, which comes from Maxwell’s displacement current.
The two are separate laws. Together they make time-dependent electric and magnetic fields give rise to each other, but neither follows from the other. Hence (R) is not the correct explanation of (A).
NCERT (2026-27):
Displacement Current – “… So, we can rephrase Faraday’s law of electromagnetic induction by saying that a magnetic field, changing with time, gives rise to an electric field. Then, the fact that an electric field changing with time gives rise to a magnetic field, is the symmetrical counterpart, and is a consequence of the displacement current being a source of a magnetic field.”